Watts to Kilowatt-Hours (kWh) Conversion Calculator
Convert watts to kilowatt-hours by entering power in watts and time in hours.
Energy in Kilowatt-Hours:
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Kevin Weekly holds a PhD in Electrical Engineering and Computer Science (EECS) from University of California Berkeley and Bachelor's degrees in electrical engineering and computer science from the University of Texas.
How to Convert Watts to Kilowatt-Hours
A kilowatt-hour, expressed as kWh or kW·h, is a measure of energy that is equivalent to 1,000 watts of power for a 1-hour time period. Thus, to convert watts to kilowatt-hours, multiply the power in watts by the number of hours, then divide by 1,000.
Watts to kWh Formula
Use the following formula to calculate energy in kilowatt-hours:
E(kWh) = P(W) × T(hrs) / 1,000
The energy E in kilowatt-hours is equal to the power P consumed in watts times the time T in hours, divided by 1,000.
For example: let’s find the kWh of 1,500 watts for 2.5 hours.
E(kWh) = 1,500 × 2.5 / 1,000
E(kWh) = 3,750 Wh / 1,000
E(kWh) = 3.75 kWh
Thus, the energy in kilowatt hours for a 1,500 power consumption over 2.5 hours is equal to 3.75 kilowatt-hours.
You can also use this formula to convert kilowatts to kilowatt-hours by not dividing by 1,000.
Electricity usage is often measured in watt-hours or kilowatt-hours, so if you can convert watts to kWh, then you can predict how much an electric appliance might cost, or how much energy is required to power it.
For example: let’s predict how much it costs to power a light bulb every hour. A 100-watt light bulb uses 100 watts of power. To convert the power in watts to kilowatt-hours, multiply 100 watts by 1 hour, then divide by 1,000 to find the energy usage in kWh.
E(kWh) = 100 W × 1 hour / 1,000
E(kWh) = 100 Wh / 1,000
E(kWh) = 0.1 kWh
If electricity costs $0.12 per kWh, then a 100-watt light bulb will cost 1.2 cents per hour that it’s on.
Try our electricity cost calculator to estimate the cost of power usage on your monthly bill.
Common Watts to Kilowatt-Hour Conversions
| Power in Watts | Energy in Kilowatt-hours | Electricity Cost (at $0.12/kWh) |
|---|---|---|
| 100 W | 0.1 kWh | $0.012 per hr |
| 200 W | 0.2 kWh | $0.024 per hr |
| 300 W | 0.3 kWh | $0.036 per hr |
| 400 W | 0.4 kWh | $0.048 per hr |
| 500 W | 0.5 kWh | $0.060 per hr |
| 600 W | 0.6 kWh | $0.072 per hr |
| 700 W | 0.7 kWh | $0.084 per hr |
| 800 W | 0.8 kWh | $0.096 per hr |
| 900 W | 0.9 kWh | $0.108 per hr |
| 1000 W | 1 kWh | $0.112 per hr |
To convert energy to watts, use our kWh to watts conversion calculator.